If I were you and had 2 acres and was looking for an excellent lawn mower, and one that would reduce my cutting time, I would look at commercial walk-behind mowers.

There are many brands to choose from that will all do an excellent job and last you forever. For your case I would look at getting a 48" to 60" deck. You can also get a sulky which allows you to stand and get pulled by the mower without having to walk.

Any of these brands are great:
Scag, Exmark, Ferris, Lesco, Hustler, Great Dane

Here is a Scag: